1. Field of the Invention
The present invention relates generally to an automatic meter reading system and method for an underground distribution line using wired/wireless communication and, more particularly, to an automatic meter reading system and method for an underground distribution line using wired/wireless communication, which gathers data about the amount of energy used by each consumer in a low-voltage section distributed in broadband over a wireless mesh network, and which sends the data about the amount of energy gathered using Frequency Division Duplex (FDD) power line communication repeating technology capable of long-distance communication between ground transformers in a high-voltage section.
2. Description of the Related Art
The automatic meter reading business is in its early infancy around the world, including Korea. In Korea, the automatic meter reading business for overhead sections has started using a power line communication method in low-voltage sections, and is on its way to achieving, in steps, nationwide automatic meter reading.
FIG. 1 is a diagram illustrating the existing automatic meter reading system for an overhead section. Referring to FIG. 1, the existing automatic meter reading system for an overhead section includes electronic watt-hour meters 10 each configured to include a detachable power line communication modem and installed in a consumer 30, a Data Concentration Unit (DCU) 40 installed on a pole 20 and configured to periodically gather meter reading data from the electronic watt-hour meters 10 of the consumers 30 and send the gathered meter reading data to a neighboring DCU 40 and an FEP/automatic meter reading server 50 and 60 including a customer information database (DB) 65, and the FEP/automatic meter reading server 50 and 60. In the existing automatic meter reading system for an overhead section, a power line communication method, an RF, or a dedicated communication line is used for communication 70 between the DCU 40 and the electronic watt-hour meters 10 of the consumers 30. An RF, a dedicated communication line, or a power line communication method is used for communication 80 between slave and master DCUs 40. A Code Division Multiple Accessing (CDMA) method, a Hybrid Fiber Coaxial (HFC) method, or a digital Trunked Radio System (TRS) method is used for communication 90 between the DCU 40 and the FEP/automatic meter reading server 50 and 60.
Meanwhile, with the recent increase in redevelopment and new city construction (in most new businesses, power is supplied via underground distribution lines), automatic meter reading for the underground section is emerging as an important issue.
Unlike in the overhead section, in the low-voltage line of the underground section, the capacity of a ground transformer (for an underground distribution line) is greater than the capacity of a pole transformer (for a ground distribution line), and therefore a single ground transformer is configured to supply power to the low-voltage consumers for up to about 500 families (about 100 to 300 low-voltage consumers). Furthermore, power line communication performance is degraded because of a wide power supply service area extending from the ground transformer to the consumers, power lines buried underground between the ground transformer and the consumers, a plurality of ground joint boxes, and multi-bifurcation on the ground rising pipe for supplying power to multi-consumer apartments. Moreover, it is impossible to immediately deal with power line communication failure because of the power lines buried underground.
For these reasons, there is a need for an effective communication method for automatic meter reading in the underground low-voltage section and for a method of efficiently obtaining data about the amount of energy using from the consumers of a maximum of 500 families over the shortest period of time.
For an overhead section high-voltage line, the deployment of a communication line, such as a coaxial cable, is easy because there are no obstacles between poles. If a wireless method is used, the desired wireless communication performance can be anticipated because Line Of Sight (LOS) can be guaranteed by attaching an antenna to the top of the pole.
For an underground high-voltage DL, however, from an economic standpoint, it is impossible in practice to deploy additional underground communication lines. Even if a wireless method is used between the ground transformers, a sufficient LOS environment cannot be provided because of the installation of an antenna at a low position and the installation of the ground transformers at locations in paths where there is a lot of vehicle and people traffic, if the distance between the ground transformers is long. Accordingly, desired wireless communication performance cannot be achieved in an underground high-voltage DL.